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46

AMMONIUM CHLORIDE

AMMONIUM   CARBONATE

The commercial product must be regarded as a mixture of ammonium
bicarbonate and carbamate, NH4HC03 + NH4-CO2-NH2 = 157 (32-5%
NH3). It forms white, fibrous, crystalline masses, emitting an odour of
ammonia and is slowly soluble in 4-5 parts of water at the ordinary
temperature.

It may contain small quantities of chlorides, sulphates, tarry matters
and fixed substances.

1.  Chlorides, Sulphates.—A solution of i gram in 10 c.c. of dilute
nitric acid should not  be  rendered  turbid by silver nitrate  or  barium
chloride.

2.  Tarry Matters.-—-2 grams should give a colourless solution with
nitric acid and the solution leave a white residue on evaporation.

3.  Volatility.—-10 grains should leave no appreciable   residue; when
heated.

4.  Determination of the Ammonia.—This is made by distillation
as described for fertilisers or by direct titration of a solution of; the carbonate
with a normal acid in presence of methyl orange ;   I c.c. N-aeid ----- 0-017
gram NH3.

Commercial ammonium carbonate contains about 31% NH.,.

AMMONIUM   CHLORIDE
NH4C1 = 53-47 (53-5)

This is put on the market in lumps or crystalline powder, the pure being
white and that for industrial purposes grey or yellowish. It may contain
as impurities, sulphates, phosphates, thiocyanates, iron, lead, and ompyreu-
matic matters.

1.  Volatility.—10 grams are heated until all white fumes disappear,
any residue being tested for heavy metals, alkalies and alkaline earths.

2.  Sulphates.—The i : 10 solution is treated with barium chloride.

3.  Phosphates.—4 grams,  dissolved in 40  c.c.  of 5% magnesium
chloride solution and treated with 6 c.c. of ammonia, should not become,
turbid, even after 12 hours.

4.  Thiocyanates .—The   i : 10  solution,  acidified  with  hydrochloric
acid, is tested with ferric chloride.

5.  Iron.—The i : 10 solution, acidified with hydrochloric acid, is tested
with potassium ferrocyanide.   Quantitative determination may be carried
out as in aluminium sulphate (q.v.).

6.  Empyreumatic and Tarry Matters.—2 grams, moistened with a
little nitric acid, are heated to clryness on a steam-bath :  in presence of
tarry products a yellowish residue remains, the residue otherwise being
white.

7.  Quantitative Determination .—The chlorine, is estimated voiumetri-
cally by Volhard's method (see Potable Waters) and the ammonia by dis-
tillation with sodium, hydroxide (sea Fertilisers).on  of